Detect change on the intersection of video and viewport.

third_party/WebKit/Source/core/dom/IntersectionGeometry.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef IntersectionGeometry_h
+#define IntersectionGeometry_h
+
+#include "platform/Length.h"
+#include "platform/geometry/LayoutRect.h"
+#include "platform/heap/Handle.h"
+#include "wtf/Vector.h"
+
+namespace blink {
+
+class Node;
+class Element;
+class LayoutObject;
+
+class IntersectionGeometry final
+    : public GarbageCollectedFinalized<IntersectionGeometry> {
+ public:
+  IntersectionGeometry(Node* root,
+                       Element* target,
+                       const Vector<Length>& rootMargin,
+                       bool shouldReportRootBounds);
+  ~IntersectionGeometry();
+
+  void computeGeometry();
+  LayoutRect targetRect() const { return m_targetRect; }
+  LayoutRect intersectionRect() const { return m_intersectionRect; }
+  LayoutRect rootRect() const { return m_rootRect; }
+  bool doesIntersect() const { return m_doesIntersect; }
+
+  IntRect intersectionIntRect() const {
+    return pixelSnappedIntRect(m_intersectionRect);
+  }
+
+  IntRect rootIntRect() const { return pixelSnappedIntRect(m_rootRect); }
+
+  DECLARE_TRACE();
+
+ private:
+  void initializeGeometry();
+  void initializeTargetRect();
+  void initializeRootRect();
+  void clipToRoot();
+  void mapTargetRectToTargetFrameCoordinates();
+  void mapRootRectToRootFrameCoordinates();
+  void mapRootRectToTargetFrameCoordinates();
+  Element* root() const;
+  LayoutObject* getRootLayoutObject() const;

[szager1, 2016/11/23 17:44:58]

If there are methods on IntersectionObserver that are no longer being used
(because you copied them into IntersectionGeometry), then please remove them
from IntersectionObserver.

[xjz, 2016/11/23 23:43:25]

Done.

+  void applyRootMargin();
+
+  Member<Node> m_root;
+  Member<Element> m_target;
+  const Vector<Length> m_rootMargin;
+  bool m_shouldReportRootBounds;
+  LayoutRect m_targetRect;
+  LayoutRect m_intersectionRect;
+  LayoutRect m_rootRect;
+  bool m_doesIntersect = false;
+};
+
+}  // namespace blink
+
+#endif  // IntersectionGeometry_h